Laws vary from state to state, but I believe in many states the foreclosure must be published in a newspaper so that anyone with an interest (meaning any owners or lien holders) knows that the property is being foreclosed on. So keep an eye on local newspapers.
It's a complicated process, due to redemption periods during which the homeowner can pay to get the property out of foreclosure, the fact that on a foreclosed property there are often numerous lien holders, it can be a bank foreclosure or a government foreclosure (for non-payment of taxes) and in some states the redemption period and the process is a bit different.
You need to talk to a Realtor or another investor familiar with it in your area since it does vary so much from state to state.